If you go deep in protection tree as cattuss suggests I'd propose a slightly revised build
like
10/0/51
Tank's 2 most important jobs is to generate threat and mitigate damage.
Related to threat apart from the obvious choices (defiance) is decent rage generation and damage enhancing talents.
It's one of the reasons Cruelty 5/5 is popular for tanks as well.
Imp heroic strike, Imp thunderclap, Imp sunder armor, 1hand specialization, focused rage and shield slam fall under the threat producing category (rage savings for use on specials and/or increased damage/threat).
Most the other talents are damage mitigation talents or utility talents.
Imp revenge is not such a hot talent for a tank imo... for 2 reasons:
1. alot of creeps in higher dungeons are immune to stuns.
2. for those that are not immune, a semi-random stun gets in the way of another important tank skill, namely moving the tanked mobs to proper locations (eg. away from crowd control so that AE can be done)
Randomly stunning a mob when you want to position it, is not very good.
So you exchange a bit mitigation (mobs don't do damage when stunned) with better control of your environment.
Imp taunt is also not essential.. if you need to spam taunt so that the 2sec make a difference there's bigger problems in your team than the 2sec can solve.
Same goes for Imp shield wall.
It's situationally useful but 5sec is not worth spending 2 points.
Imp defensive stance 3/3 is 6% less magical damage taken which is good enough not to be scoffed at.
Also tactical mastery helps alot when stance-dancing (fears, intercept, execute).
Provides alot of utility, if not 3/3 at least 2/3
There's alot of difference between switching with 10 rage and switching with 25
(looking at specials rage costs tells the tale)
Just my 2c
